美国联邦航空管理局（FAA）已发布适航指令，要求对1987架美国注册的波音737新一代（NG）客机进行水平安定面检查。
FAA Orders Inspections of Nearly 2,000 Boeing 737NG Aircraft Following Mid-Flight Pitch Incidents The Federal Aviation Administration has issued an airworthiness directive mandating horizontal stabilizer inspections for 1,987 US-registered Boeing 737 Next Generation aircraft.
该指令于11月23日生效，要求运营商检查枢轴铰链和升降螺杆是否存在过大游隙，此前有报告称飞行中出现俯仰振荡。
Effective November 23, the directive requires operators to inspect pivot hinges and the jackscrew for excessive freeplay following reports of pitch oscillations during flight.
FAA警告称，若不处理磨损可能引发安定面颤振并导致飞机可能失控。
The FAA warned that unaddressed wear could trigger stabilizer flutter and potential loss of aircraft control.
该机构拒绝了包括联合航空和阿拉斯加航空在内的承运人关于延长检查时限或修改测试方案的请求。
The agency rejected requests from carriers, including United Airlines and Alaska Airlines, to extend inspection timelines or modify testing protocols.
据估计，全美机队的检查费用将超过100万美元，不含维修成本。
Inspections are estimated to cost over $1 million across the US fleet, excluding repairs.